The emails are history.
However, this shortcut only works if keyboard shortcuts are turned on in Gmail’s tweaks.
They are turned off by default in Gmail.

Activate Gmail keyboard shortcuts with these steps:
In the upper-right corner, selectSettings(gear icon).
Scroll down to theKeyboard shortcutssection.
Scroll to the bottom of the page and selectSave Changes.

Now theShift+3keyboard shortcut is active for deleting emails.

